Synthesis and characterization of bis(4-amino-2-bromo-6-methoxy)azobenzene derivatives

• David Martínez-López,
• Amirhossein Babalhavaeji,
• Diego Sampedro and
• G. Andrew Woolley

Beilstein J. Org. Chem. 2019, 15, 3000–3008, doi:10.3762/bjoc.15.296

• conditions (pH < 1). While the low pKa makes the azonium form unsuitable, the neutral versions of these compounds undergo trans-to-cis photoisomerization with blue-green light and exhibit slow (τ1/2 ≈ 10 min) thermal reversion and so may find applications under physiological conditions. Keywords: azobenzene

Pigmentosins from Gibellula sp. as antibiofilm agents and a new glycosylated asperfuran from Cordyceps javanica

• Soleiman E. Helaly,
• Wilawan Kuephadungphan,
• Patima Phainuphong,
• Mahmoud A. A. Ibrahim,
• Kanoksri Tasanathai,
• Suchada Mongkolsamrit,
• Janet Jennifer Luangsa-ard,
• Souwalak Phongpaichit,
• Vatcharin Rukachaisirikul and
• Marc Stadler

Beilstein J. Org. Chem. 2019, 15, 2968–2981, doi:10.3762/bjoc.15.293

• -floating) cells, leading to an occurrence of reinfection once the antibiotic therapy is terminated [3][4][5]. In recent years, efforts to find new molecules that can selectively inhibit biofilms have steadily increased, based on the hypothesis that new agents can effectively disrupt biofilm formation and

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

• Aleksandr I. Kobelev,
• Nikita A. Tretyakov,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Michael Rubin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 2864–2871, doi:10.3762/bjoc.15.280

• incorrectly, and they are revised herein (for a detailed revision see Supporting Information File 1). Next, to find out whether compounds 2a and 3a were prone to undergo PTR, they were heated in open capillaries at 130 °C for 2 h, and the resulting mixtures were examined by UPLC–MS. As a result, we found that

• )thiourea, N-(3,5-dimethylphenyl)thiourea, N-(4-nitrophenyl)thiourea, and N-1-naphtylthiourea) reacted with FPD 1a unselectively, forming a mixture of four inseparable adducts (the reaction mixtures were analyzed by UPLC–MS) (Scheme 7). Unfortunately, we did not succeed to find any conditions for a

Palladium-catalyzed synthesis and nucleotide pyrophosphatase inhibition of benzo[4,5]furo[3,2-b]indoles

• Hoang Huy Do,
• Saif Ullah,
• Alexander Villinger,
• Joanna Lecka,
• Jean Sévigny,
• Peter Ehlers,
• Jamshed Iqbal and
• Peter Langer

Beilstein J. Org. Chem. 2019, 15, 2830–2839, doi:10.3762/bjoc.15.276

• find docking calculations and scoring functions. Out of 40 conformations for each compound, the conformations with lowest free binding energies and S score were selected for visualization by using Discovery studio visualizer DS [47][48]. X-ray structure determination An X-ray quality crystal of 5d was

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• can find applications in material sciences such as photopolymerization [8], or micellization photocontrol [9], since the excitation wavelength lies in the first transparency window of most biological media, a spectacular range of use in biological sciences has been explored from drug release [10

Synthetic terpenoids in the world of fragrances: Iso E Super^® is the showcase

• Alexey Stepanyuk and
• Andreas Kirschning

Beilstein J. Org. Chem. 2019, 15, 2590–2602, doi:10.3762/bjoc.15.252

• were the most expensive of all available essential oils. Exorbitant quantities of flower petals were extracted to collect the oil, used directly in cosmetic formulations or spread on laundry to generate a characteristic smell. As for musk fragrances, there was a quest in the perfume industries to find

• ]. Following this invention, many derivatives were produced to find new viable targets. These studies mostly focused on Diels–Alder cycloadditions to create structures that resemble terpenoids readily available from easily accessible and affordable starting materials like myrcene (1). One of the newly found

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• Cancer Consortium (DKTK), Heidelberg, Germany 10.3762/bjoc.15.250 Abstract Background: Silicon rhodamines are of particular interest because of their advantageous dye properties (fluorescence- and biostability, quantum efficiency, tolerance to photobleaching). Therefore, silicon rhodamines find frequent

• gave access to silicon rhodamines in poor to moderate yields, we wanted to improve these first valuable experimental results. Results: The preparation of the xanthene triflate was enhanced and several boron sources were screened to find the optimal coupling partner. After optimization of the palladium

In search of visible-light photoresponsive peptide nucleic acids (PNAs) for reversible control of DNA hybridization

• Lei Zhang,
• Greta Linden and
• Olalla Vázquez

Beilstein J. Org. Chem. 2019, 15, 2500–2508, doi:10.3762/bjoc.15.243

• first compounds here reported, may find applications in different fields such as chemical biology, nanotechnology and materials science. Keywords: azobenzene; hemithioindigo; peptide nucleic acid (PNA); photoswitch; visible-light irradiation; Introduction Light-driven control of oligonucleotide

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• host is small and is mostly related to the positions of the Pd centers (Figure S16, Supporting Information File 1). We were pleased to find that the structural features of (E-1)22 resolved by X-ray crystallography were in full agreement with a detailed analysis of the complex’s NOE spectra (see Figure

Synthesis of a dihalogenated pyridinyl silicon rhodamine for mitochondrial imaging by a halogen dance rearrangement

• Jessica Matthias,
• Thines Kanagasundaram,
• Klaus Kopka and
• Carsten S. Kramer

Beilstein J. Org. Chem. 2019, 15, 2333–2343, doi:10.3762/bjoc.15.226

• intrinsic mitochondria targeting ability, the radiolabelled analogue can find application in multimodal (PET/OI) imaging of mitochondria for diagnostic and therapeutic use in, e.g., cancer patients. (Radio)fluorination of dye 15 is the subject of ongoing research and will be presented elsewhere. (a

Perspective isomorphs – a new classification of molecular structures based on artistic and chemical concepts

• Jannis Neumann,
• Ansgar Schnurr and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2019, 15, 2319–2326, doi:10.3762/bjoc.15.224

• and to find innovative model notations, contemporary artists were asked to find new graphic ways of representing atoms. The methodical approach is not in the actual seeing, but rather the conceptualization of an epistemology using parameters, which are derived from the human visual ability. The access

Isolation of fungi using the diffusion chamber device FIND technology

• Benjamin Libor,
• Henrik Harms,
• Stefan Kehraus,
• Ekaterina Egereva,
• Max Crüsemann and
• Gabriele M. König

Beilstein J. Org. Chem. 2019, 15, 2191–2203, doi:10.3762/bjoc.15.216

• IsolatioN Device (FIND) technology allows the isolation of rare fungi from terrestrial and marine samples. The FIND comprises a multi-chambered micro agar plate, where initially only one fungal part (e.g., hyphal cell, mycelial fragment or spore) is located in each chamber. After inoculation the device is

• of them being the marine-adapted fungal strain Heydenia cf. alpina. The latter produced two new terpenoids, which are the first secondary metabolites from this genus. Keywords: FIND; fungal one-step isolation device; Heydenia cf. alpina; natural products; terpenes; Introduction Natural products

• -stimulating, and anticancer activities [2]. Since the World Health Organization (WHO) declared antibiotic resistance a global threat and urged the search for new antibiotics, the interest in fungal metabolites increased recently. In order to find new structural types, novel source organisms have to be

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• literature there are still challenges to find selective iodide receptors due to its low basicity, large size and low charge density. There is an expectation that the combination of strong hydrogen-bonding sites and a large cavity could cause strong complexation with larger halide ions [55]. In 2016 a

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

• Jürgen Krauß,
• Monika Klimt,
• Markus Luber,
• Peter Mayer and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

• subsequent dehydration to give the unsaturated lactone 3 [13][15]. In contrast to previous reports [16][17] we could not find any indication for a cleavage of the carboxanilide partial structure to give free pyrrolecarboxylic acid 5 under treatment with 6 M HCl under reflux. However, upon treatment with

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• dichloro(p-cymene)ruthenium(II) dimer or the triazolium chloride salt already observed. As a last attempt to find evidence for the ruthenacycle, a high-resolution mass spectrum was acquired directly after the reaction was completed. The most important isotopic distribution detected was at 984.4283 Da

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• could cause reproductive toxicity [33], nephrotoxicity [34], hepatotoxicity [35], myocardial damage [36] and gastrointestinal tract symptoms [37]. In order to overcome the above issues and find derivatives with good drug-like properties, extensive total syntheses and structure modifications have been

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• )2] (Figure 5f). This is in contrast to results in DMSO and indicate that DMSO is more disintegrative for noncovalent complexes based on electrostatic interactions, than the MeOH/H2O (1:1) mixture, which has a similar dielectric constant. We find this result quite nonintuitive and worth attention in

• complexes in MeOH/H2O (1:1) mixture, that have a similar dielectric constant to DMSO, reveal that in DMSO the complexes dissociate to a much higher extend. We find this result quite nonintuitive and worth attention in the context of formation of supramolecular complexes in polar environment, for which DMSO

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• structures appear to be biologically relevant, although a complete understanding of their roles is still missing [1][2][3]. At the same time, they represent versatile building blocks for artificial nano-architectures and nanodevices [4][5]. In this context, small-molecule fluorescent probes find applications

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• -CD), seven (β-CD) and eight (γ-CD) glucose units are important molecular hosts that show binding to a wide range of compounds and find applications in different fields including food and pharmaceutical industries [1][2][3][4][5]. CDs are of cone shape with two different openings: a narrower primary

Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• jars manufactured from thermoplastic materials as alternatives to Teflon, having high mechanical resistance, rigidity, and hardness, we were pleased to find that Ertalyte® displayed an excellent performance in the mechanical process. All other parameters being equal, the conversion efficiency improved

• reaction times (up to 1.5 h), did not lead to any significant improvement. However, we were pleased to find that the less hindered 2-aza-adamantane-N-oxyl (AZADO) was more effective than TEMPO in terms of conversion and yield with the model alcohol substrate, promoting an almost quantitative conversion of

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• activity. It is revealed from the literature that next to the copper, palladium catalysts in the form of salts (with or without ligands), complexes, NPs, etc. find their usage on mass scale syntheses of IPs. The role of zinc in synthetic chemistry Zinc salts being inexpensive, environmentally benign, low

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• examining the reaction of para-iodoaniline (2a) with furylcarbinol 1a in dichloromethane (DCM) in the presence of 5 mol % chiral Brønsted acid 8 (Table 1). We were pleased to find that 8 catalyzed the desired asymmetric transformation at 40 °C, affording 4-aminocyclopentenone 7a in 78% yield and a moderate

Mechanochemistry II

• José G. Hernández

Beilstein J. Org. Chem. 2019, 15, 1521–1522, doi:10.3762/bjoc.15.154

• find contributions from renowned global experts in the field of mechanochemistry spanning areas from organic mechanochemistry, supramolecular mechanochemistry to polymer mechanochemistry. Moreover, findings reported in this current thematic issue also contribute to the expansion of synthetic chemistry

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• materials in water within 8 h. Following this green methodology, we successfully synthesized 4,5-dihydropyrroloacridinones and fully aromatized pyrrolo analogues in the eco-friendly solvent water with BATA-MC as a recyclable catalyst. Moreover, some of the synthesized acridines may find medicinal

Cyclobutane dication, (CH₂)₄²⁺: a model for a two-electron four-center (2e-4c) Woodward–Hoffmann frozen transition state

• G. K. Surya Prakash and
• Golam Rasul

Beilstein J. Org. Chem. 2019, 15, 1475–1479, doi:10.3762/bjoc.15.148

• , corresponding to the vibrations of the two ethylene units in plane and out of plane). Moreover, structure 2 was also found to be notably disfavored over the structure 1 by 14.3 kcal/mol at the CCSD(T)/cc-PVTZ + ZPE level (Figure 1, Table S9 in Supporting Information File 1). Attempts to find a minimum for the